Priority is claimed to Patent Application Number 2001-32950 filed in Republic of Korea on Jun. 12, 2001, herein incorporated by reference.
1. Field of the Invention
The present invention relates to method of forming spacers in a flat panel display, and more particularly, to a method of forming spacers in a flat panel display requiring an inner vacuum such as a field emission display (FED).
2. Description of the Related Art
A flat panel display such as an FED having operating characteristics like electron emission in a vacuum space and luminescence due to excitation by the emitted electrons, includes a front plate, a rear plate, and spacers therebetween.
The flat panel display having an internal vacuum space requires a component for protecting the vacuum space and a structure for supporting the vacuum space from atmospheric pressure. The spacers are located between the front plate and the rear plate for maintaining a constant gap between the front and rear plates against the atmospheric pressure applied from outside.
In the case of a conventional FED, anode electrodes and a fluorescent layer are formed on the front plate, and electron emitting sources such as micro-tips or carbon nanotubes (CNTs), and cathodes and gate electrodes for controlling electron emission, are stacked on the rear plate.
Consequently, if the front or rear plate is deformed by the atmospheric pressure and other external pressure, the components on the front and rear plates are damaged. Especially, if the gap between the front and rear plates is changed, the emission and control of electrons will likely be severely disturbed.
Therefore, the gap between the front and rear plates has to be maintained firmly and stably in a flat panel display such as an FED. Moreover, the spacers between the front and rear plates have to be located at precise locations that do not trouble image display so as not to affect a displayed image.
For these reasons, in conventional methods of manufacturing a flat panel display, the spacers are individually formed or are stacked in a print manner. In the method of individually forming the spacers, an adhesive is applied to the spacers and the spacers are aligned and fixed onto a target at predetermined locations, for example an inner surface of the rear plate. The method includes a process of applying the adhesive, a process of aligning the spacers, and a process of loading the spacers, and thus takes a long time. Also, the rear plate is easily contaminated by an error in aligning the spacers resulting in spread of the adhesive applied to the spacers. Moreover, in the case of an FED, the precise alignment of the spacers between black matrixes of the anodes formed on an inner surface of the front plate requires expensive high-precision equipment.
Another problem is that adhesive is applied to the spacers and then the spacers are attached to the target. However, it is difficult to decide which adhesive to use for the processes and to form a pattern size of not greater than 50 xcexcm, which is a minimum value for a printing mask.
Furthermore, a printing forming method of the spacers requires repetitive printing processes for achieving high-definition and has a limit in height with high aspect ratio.
To solve the above-described problems, it is an objective of the present invention to provide a method of forming spacers in a flat panel display which precisely aligns and fixes the spacers in the flat panel display and saves time and effort in forming the spacers by simplifying processes.
To accomplish the objective of the present invention, there is provided a method of forming spacers in a flat panel display comprising preparing a plurality of spacers in a predetermined shape, preparing a substrate on which the spacers are to be attached in the flat panel display, applying a photosensitive adhesive material on an upper surface of the substrate to a predetermined thickness, aligning the spacers on the substrate to attach the spacers by using the photosensitive adhesive material, radiating light onto the substrate from above the substrate to expose portions of the photosensitive adhesive material without the spacers, and removing the exposed portions of the photosensitive adhesive material, wherein the spacers are fixed on the substrate by the photosensitive adhesive material located under the spacers.
In an embodiment of the present invention, a process of soft baking the photosensitive adhesive material by using a thermal source may be further included before radiating light onto the substrate.
Also, a drying process for drying the substrate and an annealing process for annealing the adhesive material under the spacers by which the spacers are preferably attached to the substrate are further included before removing the exposed portions of the adhesive material.
A method of forming spacers in a flat panel display according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings. In the described embodiment of the present invention, the flat panel display is a field emission display (FED) that requires an inner vacuum space and spacers between front and rear plates.